Re: [Paddlewise] How much is Alex lifting? (was: Kayak Trailers)

From: Matt Broze <mkayaks_at_oz.net>
Date: Sat, 8 Mar 2003 18:25:19 -0800
Shawn Baker wrote:

<SNIP>>>>>>Assuming the kayak's weight is spread evenly along its length, if
the
bow is on the rack exactly at the boat's 'quarter point' (1/4 the
length of the kayak back from the bow), you would be lifting half the
weight of the kayak, or 28 lbs., if you're lifting at the stern quarter
point.

If you're holding the extreme stern of the kayak, maybe your grab
handle, and the bow is over the rack at the quarter point, then you'll
be lifting with a force of 33.6 lbs, and the rack will be supporting
22.4 lbs.<<<<<<<<<<<<<<

I agree with the first paragraph but not with the second. Could you explain
how you arrived at your result? As I see it the paddler will only be
supporting one quarter of the weight, 14 pounds. This assumes, as you did
that the kayak is level and evenly distributed. If you are picking the stern
up from the ground you will be lifting more than a quarter of the weight
(depending on the kayaks angle). For instance, if the bow were straight up
you would again be lifting all the 56 pounds from the stern. If one end was
supported by the bar you would be holding half the weight. If the bar was in
the middle of the kayak the bar would be supporting all the weight. With the
bar one quarter along the boat you would be holding half of the half you
were holding when the rack was at one end. One quarter of the weight.

At first I thought the rack will be supporting the entirety of the bow
quarter weight and one-half of the three quarters that is left. That
calculation would leave the paddler supporting 3/8 of the weight.   56/4=14,
56-14=42,    42/2=21 pounds. Then I realized that the weight of the bow over
the fulcrum of the rack would also be supporting another quarter of that
kayak's weight due to the leverage. The last half of the weight would then
be shared between the rack and the paddler. My original calculation would be
correct if the bow was sawed completely off at the bar but not if the
overhanging weight of the attached bow was levering up part of the rest of
the weight.

Matt Broze
http://www.marinerkayaks.com


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Received on Sat Mar 08 2003 - 18:21:29 PST

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